This invention relates to integrated circuit modules and subassemblies of the kind which include springy contacts that are compressed to make electrical connections between two components.
In the prior art, an example of an integrated circuit module that uses compressed springy contacts to make electrical connections is disclosed in U.S. Pat. No. 4,999,023 which is entitled "High Density Low Reactance Socket." There, in FIGS. 2A and 2B, a springy contact is indicated by reference numeral 15. This springy contact 15 is comprised of a wad of wire that is held by a sleeve 14.
In FIGS. 2A and 2B of patent '023, the springy contact 15 is used to make an electrical connection between an input/output pin 20 on a packaged integrated circuit chip and a signal line 32 on a printed circuit board. This electrical connection is made by inserting the pin 20 into the sleeve 14 and pushing the pin against the springy contact 15.
When the pin 20 is pushed into the sleeve 14, the springy contact 15 is compressed parallel to the axis of the pin; and that causes the springy contact to expand perpendicular to the axis of the pin and press against the side wall of the sleeve 14. This establishes a low resistance electrical connection through the side wall of the sleeve 14 to the signal line 32.
Each springy contact 15 which is compressed exerts an opposing force against its corresponding input/output pin 20. Thus, as the total number of input/output pins 20 on a component increases, the total opposing force which is exerted on the component by all of the springy contacts 15 also increases.
As a numerical example, suppose that a component has one thousand input/output pins and each springy contact exerts an opposing force of two ounces. For that case, the total opposing force against the component is over one hundred pounds.
By increasing the total opposing force with which all of the springy contacts push against a component, a point can eventually be reached where the component will deflect or bend. If that occurs, mechanical stress is generated in the component; and this stress can produce permanent damage. For example, the stress can cause an immediate break in a microscopic signal line in or to the component; or, the stress can weaken a joint in or to the component and thereby cause a long term reliability risk.
Accordingly, a primary object of the present invention is to provide an improved integrated circuit module which uses springy contacts to make electrical connections, and in which the above stress problem is overcome.